Invertebrate taphonomy can provide significant information about the post-mortem processes that affected the fossil record. In the East Pisco Basin of southern Peru, a Panopea Ménard de la Groye, 1807 shell bed was found in the upper Miocene strata of the Pisco Formation, hinting at a peculiar biostratinomic and diagenetic history. This bed contains abundant invertebrate fossil molds cemented by dolomite. The specimens of the deep infaunal bivalve, Panopea sp., occur together with bivalves representative of shallow infaunal species (Trachycardium sp. and Dosinia ponderosa [Gray, 1838]) and balanid barnacles, which are sessile encrusters. The Panopea specimens host compound molds evidencing an abundant encrusting fauna, including serpulids, ?foraminifera, bryozoans, and barnacles that colonized the inner surfaces of the valves before their final burial. We hypothesize that short-term, storm-related processes exhumed the living bivalves, resulting in a sedimentological concentration of relatively well-preserved shells. After the death of the exhumed bivalves, the inner surfaces of the articulated Panopea shells, representing hard-substratal, sheltered environments on an otherwise unstable sandy seafloor (i.e., “benthic islands”), were colonized by different encrusting organisms. Following the final burial, dolomite precipitated, cementing the sediment infill of the valves. Lastly, a decrease of pH occurred at the sulfate reduction-methanogenesis boundary, inducing the dissolution of the shell carbonate.

Bosio, G., Bracchi, V., Malinverno, E., Collareta, A., Coletti, G., Gioncada, A., et al. (2021). Taphonomy of a Panopea Ménard de la Groye, 1807 shell bed from the Pisco Formation (Miocene, Peru) [Taphonomie d’une couche de coquilles de Panopea Ménard de la Groye, 1807 de la Formation Pisco (Miocène, Pérou).]. COMPTES RENDUS PALEVOL, 20(8), 119-140 [10.5852/cr-palevol2021v20a8].

Taphonomy of a Panopea Ménard de la Groye, 1807 shell bed from the Pisco Formation (Miocene, Peru) [Taphonomie d’une couche de coquilles de Panopea Ménard de la Groye, 1807 de la Formation Pisco (Miocène, Pérou).]

Bosio G.
;
Bracchi V. A.;Malinverno E.;Coletti G.;Basso D.
2021

Abstract

Invertebrate taphonomy can provide significant information about the post-mortem processes that affected the fossil record. In the East Pisco Basin of southern Peru, a Panopea Ménard de la Groye, 1807 shell bed was found in the upper Miocene strata of the Pisco Formation, hinting at a peculiar biostratinomic and diagenetic history. This bed contains abundant invertebrate fossil molds cemented by dolomite. The specimens of the deep infaunal bivalve, Panopea sp., occur together with bivalves representative of shallow infaunal species (Trachycardium sp. and Dosinia ponderosa [Gray, 1838]) and balanid barnacles, which are sessile encrusters. The Panopea specimens host compound molds evidencing an abundant encrusting fauna, including serpulids, ?foraminifera, bryozoans, and barnacles that colonized the inner surfaces of the valves before their final burial. We hypothesize that short-term, storm-related processes exhumed the living bivalves, resulting in a sedimentological concentration of relatively well-preserved shells. After the death of the exhumed bivalves, the inner surfaces of the articulated Panopea shells, representing hard-substratal, sheltered environments on an otherwise unstable sandy seafloor (i.e., “benthic islands”), were colonized by different encrusting organisms. Following the final burial, dolomite precipitated, cementing the sediment infill of the valves. Lastly, a decrease of pH occurred at the sulfate reduction-methanogenesis boundary, inducing the dissolution of the shell carbonate.
Articolo in rivista - Articolo scientifico
Biostratinomy; Diagenesis; Dolomite; East Pisco Basin; Encrusters; Fossil geoduck;
English
2-mar-2021
2021
20
8
119
140
open
Bosio, G., Bracchi, V., Malinverno, E., Collareta, A., Coletti, G., Gioncada, A., et al. (2021). Taphonomy of a Panopea Ménard de la Groye, 1807 shell bed from the Pisco Formation (Miocene, Peru) [Taphonomie d’une couche de coquilles de Panopea Ménard de la Groye, 1807 de la Formation Pisco (Miocène, Pérou).]. COMPTES RENDUS PALEVOL, 20(8), 119-140 [10.5852/cr-palevol2021v20a8].
File in questo prodotto:
File Dimensione Formato  
Bosio et al. 2021-CRPalevol.pdf

accesso aperto

Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Dimensione 9.42 MB
Formato Adobe PDF
9.42 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/305450
Citazioni
  • Scopus 12
  • ???jsp.display-item.citation.isi??? 8
Social impact